Roller head for cold rolling of splined shafts or gears

ABSTRACT

A rotating roller head for the cold rolling of both straight and helical mutually parallel grooves in the surfaces of approximately cylindrical work pieces, including a rotatably mounted spindle, a pair of spaced apart thrust rings mounted coaxially on the spindle and a plurality of rollers mounted between the thrust rings and revolving with the spindle in a planetary fashion. The thrust rings each have a plurality of inclined surfaces formed thereon, one for each of the rollers, with corresponding inclined surfaces on the thrust rings being equidistant one from the other and serving as mounting surfaces between which a respective one of the rollers is radially and axially fixed. The inclined surfaces are oriented to be perpendicular to the axis of its respective roller and inclined to the axis of rotation defined by the spindle. As a result, each roller is inclined at a predetermined angle to the axis of rotation defined by the spindle.

United States Patent [191 Grob et al. I

[ ROLLER HEAD FOR COLD ROLLING OF SPLINED SHAFTS OR GEARS [75] Inventors: Ernst Grob, Meilen; Hans Krapfenbauer, Ernetschwil, both of Switzerland 7 [73] Assignee: Ernst Grob, Mannedorf,

Switzerland [22] Filed: Apr. 23, 1973 [21] Appl. No.: 353,900

[30] Foreign Application Priority Data Apr. 21, 1972 Germany 2219663 [52] US. Cl. 72/78, 72/100 [51] Int. Cl B2lh 3/02 [58] Field of Search 72/77, 78, 100

[56] References Cited UNlTED STATES PATENTS 2,376,727 5/1945 Schutte 72/100 3,365,924 l/l968 Cummings 72/78 3,452,567 7/1969 Marcovitch 72/78 FOREIGN PATENTS QR APPLICATIONS 1,016,222 2/1958 Germany 72/77 June 25, 1974 Primary ExaminerRichard J. Herbst Attorney, Agent, or Firm-Edwin E. Greigg [5 7] ABSTRACT A rotating roller head for the cold rolling of both straight and helical mutually parallel grooves in the surfaces of approximately cylindrical work pieces, in cluding a rotatably mounted spindle, a pair of spaced apart thrust rings mounted coaxially on the spindle and a plurality of rollers mounted between the thrust rings and revolving with the spindle in a planetary fashion. The thrust rings each have a plurality of inclined surfaces formed thereon, one for each of the rollers, with corresponding inclined surfaces on the thrust rings being equidistant one from the other and serving as mounting surfaces between which a respective one of the rollers is radially and axially fixed. The inclined surfaces are oriented to be perpendicular to the axis of its respective roller and inclined to the axis of rotation defined by the spindle. As a result, each roller is inclined at a predetermined angle to the axis of rotation defined by the spindle.

8 Claims, 6 Drawing Figures ROLLER HEAD FOR COLD ROLLING OF SPLINED SHAFIS OR GEARS BACKGROUND OF THE INVENTION The present invention relates to the field of cold rolling, and more particularly to a rotating roller head for cold rolling which includes individual rollers to the roller head to revolve around the longitudinal axis of the roller head in a planetary fashion, with each roller carrying ring-shaped profiles provided for the cold rolling of straight or helical mutually parallel grooves in the surfaces of at least approximately cylindrical work pieces such as for example, cold rolling of splines in splined shafts or of the notches between gear teeth. In the rolling process the axis of the roller head is inclined with respect to the axis of the work piece and the work piece is not only displaced in the direction of its axis, but is also turned uniformly about its axis.

To axially displace the rollers of a roller head used in a cold rolling process is known from the disclosure set forth in German Pat. No. 1,034,127, and to incline the axis of the rollers of a roller head used in a cold rolling process to the axis of the roller head is also known from the disclosure set forth in German Pat. Nos. 1,016,222 and 1,021,322.

In the known roller head of the kind disclosed in German Pat. No. 1,021,322, the inclination of the axes of the rollers to the axis of the roller head is made possible by the fact that the rollers are mounted in special holders having conical or cylindrical shafts mating with corresponding conical or cylindrical transverse boreholes in the spindle of the roller head, the rollers being clamped to these holders by set-screws. This type of construction, however, is disadvantageous in that only a few rollers, namely in practice only two rollers, can be mounted within the roller head. This is so because of the space requirements of the holder shafts. It is nevertheless desirable to have the greatest possible number of rollers mounted within the roller head because the greater this number, the greater can be the number of individual deformations per unit time at the side of the groove for any given advancement speed of the work pieces, and therefore, the more exact will be the groove profile produced. Also, the greater the number of rollers, the greater can be the advancement speed of the work pieces so that a larger number of finished pieces per hour can be handled for any given requirement of precision.

It would therefore be desirable to have a roller head for use in cold rolling operations such as those mentioned above which provides for inclining the axis of the rollers to the roller head and yet is provided with an optimum number of rollers.

A roller head having more than two rollers is disclosed in the above cited German Pat. No. 1,034,127 as well as on page 9 of the publication Grob Kaltwalzmaschinen fur Keilwellen und Zahnrader" by Ernst Grob, Kaltwalzmaschinen, of Mannedorf (Switzerland). In these references there are disclosedmultiple roller heads containing not inclined but parallel rollers mounted within the roller head spindle itself. The axial positioning of the rollers is achieved by guiding each end face of the rollers by a face of the roller head. This structurally simple guidance of the rollers by a single surface perpendicular to the axis of the roller head is not possible with inclined rollers because the end faces of the inclined rollers will no longer be parallel to the end faces of the roller head (the single surfaces), rather they are inclined thereto and contact the faces of the roller head at only one point each. With this type of mounting, the rollers would bind and the roller head would consequently be damaged.

It would therefore be desirable to have a roller head for use in cold rolling operations such as those mentioned above which provide for inclining the axis of the rollers to the roller head without binding.

OBJECTS AND SUMMARY OF THE INVENTION It is, therefore, a general object of the present invention to provide an improved roller head for use in cold rolling operations such as those mentioned above.

it is a more specific object of the present invention to provide an improved roller head for use in cold rolling operations such as those mentioned above which includes an optimum number of rollers.

It is another specific object of the present invention to provide an improved roller head for use in cold rolling operations such as those mentioned above which provides for inclining the axis of the rollers to the roller head without binding.

It is a related'specific object of the present invention to provide an improved roller head for use in cold rolling operations such as those mentioned above according to which the rollers are mounted to the roller head so that no settable adjustment devices therefor are necessary.

These and other objects are accomplished according to the present invention by the provision of a pair of spaced-apart thrust rings each having formed thereon a plurality of inclined surfaces, one for each roller of the roller head, with each surface being oriented perpendicularly to the axis of its respective roller and inclined to the axis of rotation of the roller head so that each roller is in turn inclined at a predetermined angle to the axis of rotation of the roller head.

For achieving those advantageous arrangements in comparison to the known roller head arrangements, the present invention provides a roller head in which the individual rollers are mounted directly and fixedly at the appropriate angle in the spindle of the roller head such that no settable adjustment devices are necessary, and therefore the greatest possible number of rollers can be mounted within the roller head.

The fixed and direct position of the bearing or thrust surfaces within the spindle of the roller head also has the further and substantial advantage of resulting in a precision assembly. This is so because the inclination of the axes of the rollers is fixed during manufacture of the roller head spindle by a single setup on the machine tool, i.e., without multiple setups, and hence with the greatest possible precision. In addition, the setup cannot be dislocated by any operational error.

The provided fixed angle corresponds to the particular circular pitch of the splines or teeth desired in the work piece. Hence, for each circular pitch, or for each module, a particular roller head is required. This does not represent a disadvantage relative to the previously known roller head embodiments with adjustable roller angles because the present invention avoids the complicatedadjustments and because the change-over times are shorter since all that is necessary is a simple exchange of one roller head for another.

The present invention is also advantageous because it achieves an angular mounting of the rollers without the binding problem of the prior art. This is accomplished in that there is provided a flat butting or thrust surface on each thrust ring for each roller, which is perpendicular to the axis of its respective roller.

The essence of the present invention is, therefore, that the individual rollers be mounted fixedly and directly in the roller head at a predetermined appropriate angle; that no settable adjustment devices are necessary; that the rollers be axially positioned by a pair of spaced thrust rings which are fixed on the spindle of the roller head in the axial as well as in the circumferential direction with each being coaxial to the spindle of the roller head and located one each at each end of the rollers; that each thrust ring presents one flat butting or thrust surface which is perpendicular to the axis of its respective roller and inclined to the axis of the spindle; and that for each roller the distance between the respective inclined butting or thrust surfaces is the same.

BRIEF DESCRIPTION OF THE DRAWINGS HO. 1 illustrates partly in cross section an elevational view of a roller head according to the present invention;

FIG. 2 illustrates partly in cross section and to an enlarged scale a detailed view of a single roller in assembly between two thrust rings and corresponding spacer discs according to the present invention;

FIG. 3 is a top plan view schematically illustrating a thrust ring and roller assembly;

FIG. 4 is a development view according to one embodiment of the present invention illustrating the saw tooth-shaped sectional profile of the thrust ring surfaces along with a complete set of rollers with their spacer discs;

FIG. 5 is a development view according to another embodiment of the present invention illustrating the circumferences of the thrust rings where the thrust surfaces appear as a common straight line along with a complete set of rollers; and

FIG. 6 is a development view according to still another embodiment of the present invention illustrating the saw toothed-shaped thrust surfaces of the thrust rings along with a complete set of rollers without spacer discs.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Turning now to FIG. 1, there is shown an assembled roller head according to one embodiment of the present invention. For purposes of the present invention, attention will be focused only on the rollers and their inclined mounting. The rolling machine has two roller heads supported by, and angularly adjustable by, two roller head supports, the outline of one of which is shown in FIG. 1 at right (without a reference character). To each support there are fixed (by means not shown) two journals 1 for the roller head spindle 2. This spindle 2 has four pairs of half-cylindrical recesses (not shown) in which four rollers 3 are rotatably journalled and which give room for the roller ribs 3'. The four rollers 3 are axially held at either end by a common stationary thrust ring 4 fixed in the journal 1 and by a common rotating thrust ring 5 keyed to the spindle 2. With the embodiment shown in FIGS. 1-4 the rollers are axially held additionally by spacer discs 6 of different thickness. The journals 1 in which the roller spindle 2 is joumalled are each provided with a circular flange which takes the centrifugal forces of the rollers 3 and of the spacer discs 6. This flange of either journal has an axially slidable segment 7, which when retraced, gives way for inserting or removing the rollers and which, when reset by a set screw (not shown), completes the flange. The big cylindrical member 8 fitted on the spindle 1 at its upper end is a counter-balance weight to compensate the weight of the coupling 9 (at the lower end of the spindle) and of the articulated driving shaft (not shown), which drives the roller head spindle.

Each roller includes one or several ring-shaped circumferential ribs 3' for rolling the grooves of approximately cylindrical work pieces. These work pieces may be shafts on which straight or helical mutually parallel grooves forming splines are rolled, or they may be gears on which straight or helical mutually parallel grooves forming notches between the gear teeth are rolled. The rollers 3 are mounted to rotate in a planetary fashion about the axis a-a. The number, size and profile of the ribs depends on the size and profile of the grooves or notches to be rolled into the work piece.

The inclined butting surfaces 5' of the thrust rings 5 can be produced by radial shaping or milling of approximately sector-shaped parts of one face of each thrust ring 5 followed by grinding to conform to the required inclination. Two different embodiments of the thrust are possible.

The first embodiment consists in that the individual inclined surfaces 5' of each thrust ring 5 each lie at the same distance from the opposite flat surface 5" thereof so that in the planar development of the circumference of the thrust ring they would have the appearance of saw teeth (FIGS. 4 and 6).

In this embodiment of the thrust rings 5, two means are available to displace the circumferential ribs 3' axially between adjacent rollers 3.

One of these means is to make the rollers 3 of equal length but to axially displace corresponding circumferential ribs 3', between adjacent rollers, in their position with respect to the end surfaces of their respective rollers, by the n-th part of the rib spacing between adjacent ribs 3 measured on a respective roller, when n rollers are used.

This method is the least desirable of the two possibilities because all rollers of the roller head are different from one another in that their ribs 3 are not at the same relative position. This makes the manufacture, the stockpiling, stocking and the installation of the rollers more expensive.

The second possibility is to make all the rollers 3 equal to one another but to displace them axially by spacer discs 6. The spacer discs 6 are disposed between the end surfaces of the rollers 3 and the corresponding flat surface 5' of the thrust rings 5. The thickness of these spacer discs 6 differs from one roller to the next by llnth of the spacing of the circumferential ribs 2 measured on a respective roller, when n rollers are used. Preferably, the difference is represented by an increased thickness of the discs 6 at one end of the rollers and a corresponding decrease at the other end of the rollers. With this method the rollers 3 are interchangeable, and hence lnexpcnslve in comparison to the l'lrst possibility even though two spacer discs 4 are required per roller 3.

To avoid stock piling different rollers or spacer discs, still another embodiment of the thrust rings according to the present invention is possible. This embodiment (FIG. 5) consists in that the individual inclined surfaces 5 of each thrust ring 5 lie at an increasing distance, between adjacent rollers, from the opposite flat surface 5" of its respective thrust ring. This distance is l/nth of the spacing of the circumferential ribs 3' measured on a respective roller when n rollers are used. In the planar development of the thrust ring 5 according to this embodiment, therefore, they appear in the form of segments of a straight line, for all rollers. In this embodiment, all rollers can have a normal construction, i.e., they are symmetrical and therefore exchangeable at will and, further, no spacing discs are required. In short, the possibility of an installation error is impossible. This solution, therefore, is the most desirable from the manufacturing and operational points of view of those exemplarily disclosed.

If the roller head according to the invention is intended to be used in a rolling process in which the inclined position of the rollers is desired but not their displacement, then the necessary embodiment consists in the identity of all rollers.

That which is claimed is:

1. In a rotating roller head for the cold rolling of both straight and helical mutually parallel grooves in the surfaces of at least approximately cylindrical work pieces which are displaced relative to the roller head in the direction of their axis and uniformly rotatable about their own axes, the roller head including a rotatably mounted spindle defining an axis of rotation which is inclined with respect to the axis of, and the direction of displacement of the work pieces, and a plurality of rollers mounted to the spindle to revolve therewith about the axis of rotation of the roller head in a planetary fashion, with each roller carrying ring-shaped profiles for rolling the grooves, the improvement comprising a pair of spaced-apart thrust rings rigidly mounted coaxially on the spindle, each said thrust ring having formed thereon a plurality of inclined surfaces, one for each of said plurality of rollers, with corresponding inclined surfaces on said thrust rings being equidistant one from the other and serving as mounting surfaces between which a respective one of said plurality of rollers is radially and axially fixed, said surfaces being oriented perpendicular to the axis of its respective roller and inclined to the axis of rotation of the spindle so that each roller is in turn inclined at a predetermined angle to the axis of rotation of the spindle, said improvement being such that the plurality of rollers are mounted so that no settable adjustment devices therefor are necessary.

2. The rotating roller head as defined in claim 1, wherein the work pieces are shafts on which the straight and helically wound grooves form splines.

3. The rotating roller head as defined in claim 1, wherein the work pieces are gears on which the straight and helically wound grooves form notches between the gear teeth.

4. The rotating roller head as defined in claim 1, wherein each said thrust ring includes a flat outer surface spaced from said respective plurality of inclined surfaces, and wherein said inclined surfaces are uniformly spaced from their respective fiat outer surface so that said inclined surfaces form a saw tooth configuration in the circumferential direction of its respective ring.

5. The rotating roller head as defined in claim 4, wherein there are n rollers each of equal length and each having at least two axially spaced ring-shaped profiles defining an axial spacing therebetween, and wherein the corresponding ring-shaped profiles of adjacent rollers are displaced one from the other in the axial direction of the rollers by l/nth of said axial spacmg.

6. The rotating roller head as defined in claim 4, wherein the improvement further comprises a plurality of spacer discs, wherein there are n rollers each of equal length and each having at least two axially spaced ring-shaped profiles defining an axial spacing therebetween, and wherein each roller has a spacer disc at each axial end thereof between its axial end surface and the corresponding inclined surface of said axial end surface, with the thickness of said discs at one axial end of said rollers increasing between adjacent rollers by l/nth of said axial spacing and at the other axial end of said rollers decreasing by an equivalent llnth value between adjacent rollers, so that adjacent rollers are axially displaced one from the other by the difference in thickness of their respective spacers.

7. The rotating roller head as defined in claim 1, wherein there are n rollers each of equal length and each having at least two axially spaced ring-shaped profiles defining an axial spacing therebetween, wherein each said thrust ring includes a flat outer surface spaced from said respective plurality of inclined surfaces, and wherein said inclined surfaces are increasingly spacedfrom their respective flat outer surface by I/nth of said axial spacing so that said inclined surfaces form segments of a straight line in the circumferential direction of its respective ring.

8. The rotating roller head as defined in claim 1,

wherein the rollers are identical. 

1. In a rotating roller head for the cold rolling of both straight and helical mutually parallel grooves in the surfaces of at least approximately cylindrical work pieces which are displaced relative to the roller head in the direction of their axis and uniformly rotatable about their own axes, the roller head including a rotatably mounted spindle defining an axis of rotation which is inclined with respect to the axis of, and the direction of displacement of the work pieces, and a plurality of rollers mounted to the spindle to revolve therewith about the axis of rotation of the roller head in a planetary fashion, with each roller carrying ring-shaped profiles for rolling the grooves, the improvement comprising a pair of spaced-apart thrust rings rigidly mounted coaxially on the spindle, each said thrust ring having formed thereon a plurality of inclined surfaces, one for each of said plurality of rollers, with corresponding inclined surfaces on said thrust rings being equidistant one from the other and serving as mounting surfaces between which a respective one of said plurality of rollers is radially and axially fixed, said surfaces being oriented perpendicular to the axis of its respective roller and inclined to the axis of rotation of the spindle so that each roller is in turn inclined at a predetermined angle to the axis of rotation of the spindle, said improvement being such that the plurality of rollers are mounted so that no settable adjustment devices therefor are necessary.
 2. The rotating roller head as defined in claim 1, wherein the work pieces are shafts on which the straight and helically wound grooves form splines.
 3. The rotating roller head as defined in claim 1, wherein the work pieces are gears on which the straight and helically wound grooves form notches between the gear teeth.
 4. The rotating roller head as defined in claim 1, wherein each said thrust ring includes a flat outer surface spaced from said respective plurality of inclined surfaces, and wherein said inclined surfaces are uniformly spaced from their respective flat outer surface so that said inclined surfaces form a saw tooth configuration in the circumferential direction of its respective ring.
 5. The rotating roller head as defined in claim 4, wherein there are n rollers each of equal length and each having at least two axially spaced ring-shaped profiles defining an axial spacing therebetween, and wherein the corresponding ring-shaped profiles of adjacent rollers are displaced one from the other in the axial direction of the rollers by 1/nth of said axial spacing.
 6. The rotating roller head as defined in claim 4, wherein the improvement further comprises a plurality of spacer discs, wherein there are n rollers each of equal length and each having at least two axially spaced ring-shaped profiles defining an axial spacing therebetween, and wherein each roller has a spacer disc at each axial end thereof between its axial end surface and the corresponding inclined surface of said axial end surface, with the thickness of said discs at one axial end of said rollers increasing between adjacent rollers by 1/nth of said axial spacing and at the other axial end of said rollers decreasing by an equivalent 1/nth value between adjacent rollers, so that adjacent rollers are axially displaced one from the other by the difference in thickness of their respective spacers.
 7. The rotating roller head as defined in claim 1, wherein there are n rollers each of equal lenGth and each having at least two axially spaced ring-shaped profiles defining an axial spacing therebetween, wherein each said thrust ring includes a flat outer surface spaced from said respective plurality of inclined surfaces, and wherein said inclined surfaces are increasingly spaced from their respective flat outer surface by 1/nth of said axial spacing so that said inclined surfaces form segments of a straight line in the circumferential direction of its respective ring.
 8. The rotating roller head as defined in claim 1, wherein the rollers are identical. 